Preparation of cyanoalkylsilanes employing trihydrocarbyl phosphine catalysts



United States Patent PLOYING TRIHYDROCARBYL PHOSPHINE CATALYSTS Victor B. Jex and John E. McMahon, Buifalo, N.Y., as-

signors to Union Carbide Corporation, a corporation of New York No Drawing. Application June 28, 1957 Serial No. 668,621

17 Claims. (Cl. 260-4483) This invention relates to new compositions of matter comprising the beta-cyanoethylsilanes and to a process for their production. More particularly, the invention is concerned with beta-cyanoethylsilanes which contain at least one hydroylzable group bonded to the silicon atom thereof as new compositions of matter and to a process for their production.

This application is a continuation-in-part of application Serial No. 555,201, filed December 23, 1955.

By reacting alpha-beta olefinically unsaturated nitriles of the type represented by acrylonitrile, methacrylonitrile, crotononitrile and the like with a silane containing at least one hydrogen atom and at least one hydrolyzable group bonded to the silicon atom thereof there is produced a mixture of reaction products from which an alpha-cyanoalkylsilane can be recovered. The overall reaction which takes place can be graphically represented by the following equation, which depicts, for the purpose of illustration,-the reaction between acrylonitrile and trichlorosilane. w

moi-export Heron n2o-oHoN H Sick The present invention is based on our discovery that an alpha-beta olefinically unsaturated nitrile of the type represented by acrylonitrile, methacrylonitrile, crotononitrile and the like can be caused to react with a silane, containing at least one hydrogen atom and at least one hydrolyzable group bonded to the silicon atom thereof, in the presence of a catalyst to produce a beta-cyanoalkylsilane by the addition of a silyl group to the beta carbon atom of such nitrile, that is the olefinic carbon atom further removed from the cyano group of the nitrile, and by the addition of a hydrogen atom to the alpha carbon atom of such nitrile, that is the vicinal olefinic carbon atom. Based on our discovery we have further found that any olefinic nitrile can be caused to react with a silane, containing at least one. hydrogenatom and at least one hydrolyzable group bonded to the silicon atom thereof, in the presence of a catalyst to produce a cyanoalkylsilane by the addition of a silyl group to the olefinic carbon atom further removed from the cyano group of the nitrile a and by the addition of a hydrogen atom to the olefinic carbon atom closer to the-cyano group of the nitrile.

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Our process can be carried out by forming a mixture of the olefinic nitrile, a silane containing at .least one hydrogen atom and at least, one hydrolyzable group bonded to the silicon atom thereof and a small or catalytic amount of a hydrocarbyl substituted phosphine as catalyst for the reaction and heating the mixture to a temperature suflflciently elevated to cause the starting materials to react. There results or is produced a cyanoalkylsilane by the addition of a silyl group to the olefinic carbon atom of the nitrile further removed from the cyano group and by the addition of a hydrogen atom to the olefinic carbon atom of the nitrile closer to the cyano group. .By the term hydrocarbyl as used herein, is meant a monovalent organic group composed of carbon and hydrogen and includes saturated as well as unsaturated groups.

The silane starting materials containing at least one hydrogen atom and at least one hydrolyzable group bonded to the silicon atom thereof, which we employ in our process can be represented by the following general formula:

(3n) wherein R represents a hydrogen atom or a hydrocarbyl group, preferably a saturated aliphatic or cycloaliphatic hydrocarbyl group as for example, an alkylgroup such as methyl, ethyl, propyl, butyl, pentyl and the like and a cycloalkyl group such as cyclopentyl, cyclohexyl, methylcyclopentyl, ethylcyclohexyl, and the like or an aromatic hydrocarbyl group as for example, an aryl group such as phenyl, naphthyl, tolyl, methylnaphthyl and the like, X is a hydrolyzable group such as a halogen atom, preferably a chlorine atom, or. a hydrocarbyloxy group, preferably an alkoxy or an aryloxy group such as methoxy, ethoxy, propoxy, phenoxy and the like, and n is a whole number having a value of from 0 to 2. Illustrative of the silane starting materials are 'trichlorosilane, triethoxysilane, dichlorosilane, diethoxysilane, monochlorosilane, monoethoxysilane, methyldichlorosilane, ethyldiethoxysilane, diethylethoxysilane, dlimethylchlorosilane, butylethylchlorosilane, phenyldichlorosilane, phenylethylethoxysilane, dipropylphenoxysilane and the like.

The olefinic nitrile starting materials which we can employ in the practice of our invention are the aliphatic mono-olefinic nitriles which contain from three to ten carbon atoms to the molecule. Illustrative of such ole- The overall reaction which takes place canbe graphically represented byathe following equations which depict for the purpose of illustration the reaction between acrylonitrile and trichlorqsilane and thereaction between allyl cyanide and triethoxysilane:

I (EtO);Si H (2 finic nitriles are acrylonitrile, methacrylonitrile, allyl cyanide, 1-cyano-3-butene, l-cyano-4-pentene, l-cyano-lhexene and the like. Our preferred nitrile starting materials are the alpha-beta olefinically unsaturated nitriles, namely those nitriles in which the unsaturated grouping is directly bonded, through one of the carbon atoms thereof, to the carbon atom of the cyano group. Such olefinic nitriles are commonly known as the vinyl-type cyanides and can be represented by the general formula:

i R- CH=GCN where R can be a hydrogen atom or an alkyl group as for example methyl, ethyl, propyl, butyl and the like and atom'of the starting silane to the vicinal olefinic carbon substituted phosphines are triethylphosphine, methyldi-' ethylphosphine, tri-n-butylphosphine, triphenylphosphine, and the like. 7

We have found that the amount of the catalyst employed in our process is not narrowly critical. Thus, amounts of the trihydrocarbylphosphines of from as little as about 0.2, part to as much as about 10 parts by weight per 100 parts of the total weight of the starting materials can be favorably employed. We preferably employ the catalyst in an amount of from about 0.3 part to about 3 parts by weight per 100 parts of the total weight of the nitrile and silane starting materials. Amounts of the trihydrocarbyl substituted catalysts in smaller or greater quantities than the favorable range can also be employed. However, no commensurate advantage is obtained thereby.

The olefinic nitrile and silane starting materials can be employed in our process in amounts which can vary from about one-half to 2 moles of the nitrile per mole of the silane. Preferably, the reactants are employed in equimolar amounts. Amounts of either of the starting materials in excess of the ratios set forth above can also be employed; however, no commensurate advantage is obtained thereby.

To facilitate observation and at the same time to favor closer control of the reaction conditions, most of our experimental work was carried out in pressure vessels or bombs, with agitation being provided if desired by continuous shaking. Similar results can be obtained with flowing reactants in apparatus 'of known design permitting the maintenance of a closed system. .In the reactions with which our invention is concerned, it is desirable to maintain sufliciently high concentrations of the reactants (as measured for example in moles per liter of reaction space) to promote effective contact between the molecules to be reacted. When one of the reactants is a gas, or a liquid readily volatile at the reaction temperature, and the reaction mixture is permitted to expand freely on heating, the concentration-of that reactant will fall to a low value thusconsiderably slowing the reaction rate. If, however, the reactants are charged to a closed vessel which is sealed before heating the initial concentration of any reactant falls off through its consumption by the reaction. If a reactant is a gas, it may be desirable to charge the reaction vessel to a considerable pressure to secure an adequate concentration and reaction rate, and also to supply enough of the reactant to produce an acceptable quantity of the product.

Thetemperatures which can be employed in carrying out our process are not narrowly critical and can vary over a wide range. For example, temperatures as low as 40 C. and as high as 350 C. can be advantageously employed' When conducting the process of the invention in a closed vessel a temperature in the range from about 75 C. to about 250 C. is preferred. Under such conditions, a reaction period of from about two'to about five hours is suitable. Temperatures of from about 175 C. to about 300 C. are preferred when conducting the. process in apparatus which provides for the flow of the reactants and products while maintaining the conditions of a closed system. In such systems, Where the pressure may range from atmospheric up to 40001poundsper square inch and higher, the time required for the reaction to take place can be as short as 0.005 minute.

In carrying out the process of our invention the product initially obtained comprises a mixture of compounds including the main cyanoalkylsilane as well as some unreacted nitrile and unreacted silane starting compounds. The cyanoalkylsilane product, formed by the addition of a silyl group to the olefinic carbon atom of the nitrile further removed from the cyano group and by the addition of a hydrogen atom to the olefinic carbon atom closer to the cyano group, which contains at least one hydroylzable group bonded to the silicon atom thereof, as for example beta-cyanoethyltrichlorosilane, can be recovered therefrom by distillation which is preferably conducted under reduced pressure.

The mechanism of our overall reaction wherein the silyl group is attached to the olefinic carbon atom of the starting nitrile further removed from the cyano group and the hydrogen atom is attached to the olefinic carbon atom closer to the cyano group with the apparent suppression of other addition or reaction products is not known with certainty or fully understood. It is known that upon heating our reactants in the absence of a trihydrocarbylphosphine as catalyst other reactions can take place such as: the formation of both siliconand non-silicon-containing free radicals and complexes, the homopolymerization of the starting nitrile, and even the disproportionation of the starting silane has been observed. In addition, it is known that in the absence of our catalysts, our preferred starting materials can react to produce a mixture from which an alpha-cyanoalkylsilane, wherein the silyl group is attached to the olefinic carbon closer to the cyano group and the hydrogen atom is attached to the other olefinic carbon more remote from cyano group, can be recovered with no beta addition products being detected. One possible explanation for the course which our reaction follows when a silane and an olefinic nitrile react in the instance where the nitrile is a vinyl-type cyanide is that the addition of the silyl group to the olefinic carbon atom more removed from the cyano group of the nitrile occurs through an ionic mechanism while the addition of the silyl group to the olefinic carbon atom closer to the cyano group of the nitrile occurs through a free radical mechanism. If such is the case, then the activation energy required for the reaction between our starting nitriles and silanes to proceed by a free radical mechanism is considerably less than that required to cause the reaction to proceed by an ionic mechanism. Consequently, in the absence of our catalyst the reaction between an olefinic nitrile and a silane, as for example acrylonitrile and trichlorosilane, will produce the alpha-addition product namely, alpha-cyanoethyltrichlorosilane. On theother hand, our trihydrocarbylphosphines apparently have the effect of markedly decreasing the activation energy required for the reaction to proceed by an ionic mechanism and therefore when employed in such reactions, as for example in the above acrylontriletrichlorosilane reaction, result in the production of beta-cyanoethyltrichlorosilane.

When the olefinic nitrile is of the type represented by allyl cyanide, thatis, where the unsaturated grouping" 3-- 7-) V is removed by one or more carbon atoms from the cyano group, our catalyst also functions in promoting the reaction thereof with our silane starting materials to produce addition products by the addition of a silyl group to the olefinic carbon atom more removed from the cyano group, and by the addition of a hydrogen atom to the olefinic carbon closerto the cyano. group. By way of lllustration, gamma-cyanopropyltrichlorosilane is prepared by reacting allyl cyanide with trichlorosilane in accordance with the subject process.

Our trihydrocarbylphosphines have been found to promote exceptionally high conversioy filld @fliciencies in nitrile.

the formation of beta-cyanoalkylsilanes in accordance with our invention. .The trihydrocarbylphosphines are highly selective in promoting the addition of the silyl group of the starting silane to the olefinic carbon atom further removed from the cyano group of the starting Thus, the cyanoalkylsilane products obtained herein are substantially completely composed of only beta-cyanoalkylsilanes with very slight, if any, amounts of alpha-cyanoalkylsilane.. We have found, on the other hand, that other trihydrocarbyl substituted hydrides, e.g. the tertiary amines, the trihydrocarbylarsines, the trihydrocarbylstibines and the trihydrocarbylbismuthines are not capable of providing such high yields, if any yield at all, and provide at the mostonly approximately one half the yields obtained when employing trihydrocarbylphos, phines catalysts under similar reaction conditions. Moreover, even when cyanoalkylsilanes are obtainedthrough the use thereof, the trihydrocarbylarsine, -stibine and -bismuthine catalystsare not very selective in directing solely beta-addition of the silyl group and mainly provide mixtures of alphaand. beta-substituted oyanoalkylsilanes which must then be separated. The trihydrocarbylphosphines are additionally advantageous in that they do not participate in or promote, to any great extent, undesirable side reactions, either by reaction with the starting nitrile or the starting silane or both; Of particular note in this regard is the lack of complexing with the starting materials and the complete absence, during the reaction, of insoluble, solid complexes which reduce the yield, consume the catalyst and create problems associated with the presence of solids in a gas, liquid or liquid-gas phase reaction. Thus, our reaction mixtures containing the trihydrocarbylphosphines are homogeneous with uniform distribution of catalyst, are easily handled, e.g. by pumping without clogging due to solids, are free of complications associated witlnthe handling of slurries and retain the catalyst in solution so as to promote its effectiveness and prevent its loss. In these respects, trihydrocarbylphosphines are vastly superior to other trihydrocarbyl substituted metal hydrides, for example, the tertiary amines which have been found to vigorously complex with the starting silanes to form solids and with reaction mixtures containing the starting silanesand nitriles to form insoluble, White solids. The trihydrocarbylphosphines have been found to be further superior to other trihydrocarbyl substituted hydrides, such as tertiary amines, in that much less disproportionation of the starting silanes takes place when the phosphines are employed as catalysts. Such disproportionation, which is most evident when tertiary amines are employed as catalysts, is manifested in the formation of high-boiling materials resulting in the nonproductive consumption of the starting silane, reduction in yield and complications in the recovery of product.

Bis(cyanoalkyl) silanes are produced in the practice of the process of our invention when ourstarting nitriles are reacted with silanes containing at least two hydrogen atoms bonded to the silicon atom thereof. In such in,- stances the nitrile starting material is preferably employed in an amount which is atleast twice the number, of moles of the starting silane. Along with the desired bis cornpound, there is present in the reaction mixture the cyanoalkyl'hydrogen-silane. By way of illustration, when two moles of acrylonitrile are reacted with one mole of dichlorosilane in the presence of our trihydrocarbyl substituted phosphines there is obtained his (beta-cyanoethyl) dichlorosilane I and beta-cyanoethylhydrogendichlorosilane. Alternatively, cyanoalkyl hydrogen silanes can be used as starting materials for producing bis(cyanoalkyl) silanes. For example, the beta-.cyanoethylhydrotion, the tris compounds can also be obtained by using as the starting material a silane containing at least three hydrogen atoms bonded to the silicon atom thereof. The tris compounds can be prepared by attaching the three cyanoalkyl groups to each silane molecule in a single re action step, in two successive reaction steps or in three successive reaction steps.

Our beta-cyanoethylsilanes can be graphically depicted by the following general formula:

where R represents a hydrogen atom or a hydrocarbyl group, preferably a saturated aliphatic hydrocarbyl group as for example, an alkyl group, such as methyLethyl, propyl, butyl, pentyl, and the like; a cycloalkylgroup such as cyclopentyl, cyclohexyl, methylcyclopentyl, ethylcyclohexyl, and the like or an aryl group such as naphthyl, tolyl, methylnaphthyl and the like, X is'a hydrolyzable group such as a halogen atom, preferably a chlorine atom or a hydrocarbyloxy group, preferably an alkoxy or an gendichlorosilane is further reacted with an additional amount of the starting nitrile to foirn bis(beta-cyanoethyl) dichlorosilane. In this manner the two cyanoalkyl groups are attached to each silane molecule by two distinct reaction steps. Still in accordance "with our inven:

aryloxy group such as methoxy, ethoxy, propoxy, phen oxy and thelike, m is a whole number having a value of from 1 to 3 and n is a whole number having avalue of from 0' to 2, with the sum of m and n being not greater than 3.

Illustrative of such new cyanoalkylsilanes are betacyanoethyltrichlorosilane, beta-cyanoethyltriethoxysilane, beta cyanoethylmethyldichlorosilane, beta cyanoethylmethyldiethoxysilane, beta-cyanoethylethyldichlorosilane, beta-cyanoethylethyldipropoxysliane, beta-cyanoethylhydrogendichlorosilane, beta-cyanoethylhydrogendiethoxysilane, beta-cyanoethylphenyldichlorosilane, beta-cyanoethylphenyldipropoxysilane, beta-cyanoethyldimethylchlorosilane, beta-cyanoethyldiphenylchlorosilane, beta-cyanoethylrnethylhydrogenchlorosilane, beta-cyanoethylphenylhydrogenchlorosilane, beta cyanoethyldiphenylethoxysilane, beta-cyanoethylmethylhydrogenethoxysilane, betacyanoetliylphenylhydrogenethoxysilane, bis(beta-cyanoethyl) diethoxysilane, bis (beta-cyanoethyl) dichlorosilane, bis beta-cyanoethyl methylethoxysilane, bis beta-cyanoethyl)phenylchlorosilane, bis(betapyanoethyl)hydrogenchlorosilane, tris(beta-cyanoethyl)chlorosilane, tris.(beta cyanoethyDethoxysilane and the like. I

Our beta-cyanoethylsilanes lend themselves to a wide variety. of commercial applications. By way of illustration, the beta-cyanoethylhydrocarbyloxysilanes, as for example beta-cyanoethyltriethoxysilane, can be employed as the starting material in the preparation of the corre spending gamma-aminopropylhydrocarbyloxysilanes, as for example gamma-aminopropyltriethoxysilane, which latter compounds have. been found extremely useful as sizes for fibrous glass materials when employed in combination with epoxy, phenolic and melamine condensation resins for the production of fibrous glass laminates. The production of aminopropylhydrocarbyloxysilanes is accomplished by hydrogenating the new compounds of the present invention under pressure and in the presence of a catalyst at a temperature of about C. The reaction that takes place can be depicted by the following equation which illustrates the hydrogenation of beta-cyanoethyltriethoxysilane The beta-cyanoetliylchlorosilanes of our invention can be employed as the, starting materials in the preparation Our beta-cyanoethylsilanes, by virtue of the hydrolyz able group or groups bonded tothe silicon z'atorn'thereof,

7 can be hydrolyzed to beta-cyanoethylpolysiloxanes. Hydrolysisof oursilanes is accomplished by the addition of such silanes to water. We prefer to carry out the hydrolysis reaction by first mixing the substituted silane with a liquid organic compound completely miscible therewith, as for example, diethyl ether and adding such mixture to a medium comprising a mixture of water, ice and the organic ether. By way of illustration, beta-cyanoethylpolysiloxane is produced byforming a mixture of beta-cyanoethyltrichlorosilane with diethyl ether, as for example, 100 parts of the silane and 20 parts of the ether and adding the mixture to a beaker containing a mixture of water, ice and diethyl ether. There results a two-phase system, one of the phases being aqueous hydrochloric acid and the other phase being beta-cyanoethylpolysiloxane in diethyl ether. The aqueous hydrochloric acid phase is decanted and the siloxane-solvent phase washed with water until the washings are neutral. Upon evaporation of the ether or other solvent from the non-aqueous phase, preferably under reduced pressure there is obtained as a residue 2. partially condensed beta-.

cyanoethylpolysiloxane. The partially condensed material can be completely cured to a hard brittle polymer. In alike manner, the difunctional beta-cyanoethylsilanes as well as the mono-functional beta-cyanoethylsilanes can be hydrolyzed to polymeric compositions.

Beta-cyanoethylpolysiloxanes, prepared by the hydrolysis of the compounds of our invention, can be graphically depicted by various general formulae depending upon the functionality of the starting monomer. By way of illustration, our trifunctional silanes upon hydrolysis become polysiloxanes containing the unit:

which, when in a completely condensed state are represented by the formula:

and our difunctional silanes upon hydrolysis become polysiloxanes containing either unit:

, I [NCCHzCHzSlO or the unit [(NCCH CH Si] which when in a completely condensed state are represented by the formulae:

[NO OHaCHzdiO1v while our monofunctional silanes upon hydrolysis become polysiloxanes containing any of the units:

which, when in a completely condensed state are represented by the-formulae:

or a hydrocarbyl group such as an alkyl of aryl group while the letters w and y represent whole numbers with a w having a value of at least 4 and y having'a value of at least 3.

The difunctional beta-cyanoethylsilanes of our invention form cyclic as well as linear polymers upon hydrolysis. For example, beta-cyanoethylmethyldiethoxysilane upon hydrolysis produces in addition to a linear betacyanoethylmethylpolysiloxane various cyclic siloxanes such as the cyclic trimer, tetramer, pentamer and hexamer of beta-cyanoethylmethylsiloxane. 'The new polymeric beta-cyanoalkylsiloxanes of our invention find use in numerous applications depending upon the type of polymers prepared. By way of illustration, the trifunctional substituted silanes upon hydrolysis and complete condensation become highly cross-linked, hard, infusible polymers. Such polymers are useful as protective coatings for metallic surfaces which are normally subjected to temperatures as high as 200 C. The new linear and cyclic siloxanes find use as oils inthe lubrication of moving metal surfaces. The 'new monofunctional silanes as well as their hydrolysis products, namely the corresponding dimers, can be employed as endblocking compounds to control the chain length of linear beta-cyanoalkylsilanes in the production of oils.

The following examples are illustrative of the present invention.

Example 1 To a 50 cc. steel pressure vessel were added 0.15 mole (20.3 grams) of trichlorosilane, 0.15 mole (8. grams) of acrylonitrileand 0.56 gram (2 percent by weight) of triphenylphosphine. The vessel was sealed and heated, while being rocked, to a temperature of 200 C. fora period of two hours. Afterheating, the vessel was cooled to room temperature, the product removed therefrom and placed in a flask connected to a distillation column. The contents of the flask were heated to its boiling temperature under reduced pressure and there was obtained 15.85 grams of beta-cy-anoethyltrichlorosilane boiling at a temperature of to C. under a reduced pressure of 5 to 7 mm. Hg. Beta-cyanoethyltrichlorosilane was identified by infra-red analysis and by analysis for hydrolyzable chlorine (obtained 56.0 percent by Weight, theory 56.4 percent by weight). Alpha-cyanoethyltrichlorosilane was not produced by the reaction. The 1585 grams of beta-cyanoethyltrichlorosilane represented a yield of 56.0 percent based on the total number of moles of the starting materials.

Example 2 I To a 300 cc. steel pressure vessel were added 0.9 mole (120.5 grams) of trichlorosilane, 0.9 mole (48.0 grams of acrylonitrile and 3.36 grams (2 percent by weight) of triphenylphosphine. The vessel was sealed and heated,

while being rocked, to a temperature of C. for a period of one-half hour. After heating the vessel was cooled to room temperature, the product removed therefrom and placed in a flask connected to a distillation The contents of the flask were heated to its obtained 111.2 grams of beta-cyanoethyltrichlorosilant? boiling at a temperature of 75 to 80 C. under a reduded pressure of 5 to 7 mm. Hg. .Beta-cyanoethyltrichlorosilane was identified by infra-red analysis and by analysis for hydrolyzable chlorine (obtained 55.9 percent by weight, theory 56.4 percent by weight). 'Alpha-cyanoethyltrichlorosilanev was not producedby the reaction. The 111.2 grams of beta-cyanoethyltrichlorosilane represented a yield of 66 percent based on the total number of moles of the starting materials. 7

Example 3' Following the procedure disclosed in Example 1 equal molar amounts of trichlorosilane and acrylonitrile and 1 percent by weight. of the reactants of triphenylphosphine a culated for each of the periods. "appear in the table below. v

T015300 1. flask :ec iuipped: wart-a V mechanical stirrer, and. droppinglfunnel: "was .added a werejheated' ina steel pressurevesselat a temperature of 75 C. for a period of two hours. The product was fractional ly distilled andobtained an amount of beta-cyanoethyltrichlorosilane equivalent to a yield of 12.7 percent by Weight of the starting materials.

Example 4 To each of three steel pressure vessels were added equal molar amounts of trichlorosilane and acrylonitrile and 0.5, 1.0 and 2.0 percent by weight of the reactants respec: tively of triphenylphosphine. The vessels were. sealed and heated to a temperature of 150 C. for a period of two hours. After heating the vessels were cooled and the product obtained from each of the vessels fractionally distilled. A yield of 59 percent based on the total number ofmoles of starting material of beta-cyanoethyltrichlorosilane was obtained from the reaction conducted in the presence of 0.5 percent of the catalyst anda yield 'of 67.2 percent based on the total numberof moles of starting materials of beta-cyanoethyltrichlorosilane obtained fromthe reaction conducted in the presence of 1.0 percent of the catalyst while a yield of 65.3 percent based on the total number of moles of starting materials of betacyanoethyltrichlorosilane obtained from the reaction conducted inthe presence of2 percent of the catalyst.

Example 5 Following the procedure disclosed in Example 4 equimolar amounts of acrylonitrile, trichlorosilane and 2 percent by weight thereof of triphenylphosphine were heated, in separate pressure vess'els,"to a temperature of 40 C. for a period of 18 hours, 50 C. for a period of 20 hours and 60 C. for a period of 26 hours. Basedon the total number of moles of startingmaterials, beta-cyanoethyltrichlorosilane was obtained in an amount of 7.9 percent from the reactionconducted at C., 23.8 percent from the reaction conducted at C. and 66m5 percent from the reaction conducted at C;

. 1 Example 6 I To illustrate the continuous production of cyano-alkylsila'nes of the process ,of our. invention the following experiment :Was conducted. i

To an eight gallon stainless steel feed vessel were charged equal molar amounts of trichlorosilane', acrylonitrile and 1 percent by weight thereof of triphenylphosphine. The contents of the vessel were fed to a pump which in turn fed them to a reactor positioned within an electrically heated :salt bath. The. reactorconsisted of four vertical five foot lengths of stainless steel tubing /27. CD. by A1.I.D.) welded into top and bottom headers. The pressurewithin the reactor is controlled by an automatic bfiCk'lPIBSSUIG valve operated by an air controller. The stream of .beta-cyanoethyltrichlorosilane from the reactor was directed to a refrigerated product collector and phase separator from which -it was periodically removed and analyzed. The'contimr ous reaction: was conducted for periods of time under various conditions of temperature and pressure with the percent conversion and efIiciency of the reaction cal- The values obtained Conversionto Efficiency Pressure eta-Oyano- (based on Temp. (01) (p.s.i.) ethyl-Tri- BS101 K chlorosilane (Percent) (Percent) 1,500 60.0- 73.2 $2,000 13.8 7 6.1 3,000 78.2 a a (79.2 4,000- to. 74.9

Example 7 condenser, a

solution comprising 0.20 mole (36.4 grams) of betacyanoethyltrichlorosilane dissolved in 75 ml. of anhydrous ethyl ether While stirring the mixture, 0.58 mole (26.7 grams) of ethanol was slowly added by means of the dropping funnel. After the addition, the mixture was continually stirred for about three hours after which time it was heated to its boiling temperature under reduced pressure. There was obtained 24.2 grams of beta-cyanoethyltrietlioxysilane boiling at 102 C. under a reduced pressure of 3.8 Hg. f' Beta-cyanoethyltriethoxysilane has a density (1 of 0.970 and a refractive index n i'of 1.4153. Elemental analyssfor carbon, hydrogen, silicon, nitrogen and ethoxy content were also conducted with the values obtained listed in the table below where they are compared with the corresponding calculated values for. betacyanoethyltriethoxysilanez Beta-cyanoethyltriethoxysilane Found Calculated Example 8 To a 300 cc. 'steel pressure vessel were added 0.58 mole (39 grams) of methacrylonitrile, 0.58 mole (78 gramsyof trichlorosilane and 2 percent by weight of the reactants of triphenylphosphine. The vessel .was sealed and heated to a temperature of C. for a period of two hours. The product obtained, which was light green in color, was placed in a 250 ml. distilling flask and fractionally distilled under a reduced pressure through a:Vigreaux column. Therewas obtained 41.4 grams of beta-cyanopropyltrichlorosilane boiling at a temperature of 74 to 77 C. under a reduced pressure of 3, nrmQHg. Beta-cyanopropyltrichlorosilane ,has a refractive index 2 of 1.4583 and a density 114 of1.28. Beta-cyanopropyltrichlorosilane was identified by infrared analysis as well as byj', analysis for hydrolyzable chlorine (obtained 51.8 percent by weight, theory 52.5 percent by,weig'ht) r Example To .a 300 cc. steel pressure vessel were added 0.78 mole (89. 7 grams) of methyldichlorosilane, 0.78 mole (41.5 grams.) of acrylonitrile and 2 percent by weight of the reactants of triphenylphosphine. The vessel was sealed and heated, while being rocked, to a temperature of 150 C. for a period of two hours. After heating the vessel was cooled to room-temperature,: the. product removed therefrom and placed in a flask connected to a distillation: column. The contents of the flask were heated to its boiling temperature under reduced pressure and there was obtained 11.6 grams of beta-cyanoethylmethyldi chlorosilane boiling at a temperature of 45 cyanqethylmethyldichlorosilane was red, analysis.

Example 10 Following the procedure set forth in Example 9, 0.46 mole (59 grams) of mcthyldiethoxysilane, 0.46 mole .(25 grams) of acrylonitrile, and 2 percent by weight of the reactants of triphenylphosphine were heated in a pressure vessel at a temperature of 200 C. for a period of five hours. The product was placed in a flask, connected to a fractionating column and heated to its boiling temperature under a reduced pressure. There was.

obtained 1 gram of beta-cyanoethylrnethyldiethoxysilane whichwas clear yellow incolor. r r

- Example 11 Following'the procedure disclosed in Example 6, 0.9 mole (116.1 grams) of ethyldichlorosilane, 0.9 mole (48 grams) of acrylonitrile and 2. percent by weight of the reactants of triphenylphosphine were heated in a pressure vessel at a temperature of 150 .C. for a period of two hours. The product. obtained was placed in a flask connected to a fractionating column and heated to its boiling temperature under reduced pressure. There was obtained.23.2 grams, of beta-cyanoethylethyldichlorosil'ane boiling at a temperature of 50to 60 C. under-a reduced pressure of'1 mm. Hg. Beta-cyanoethylethyldichlorosilane was also identified by infra-red analysis- Example 12 To a 300 ccjsteel pressure vessel were added 0.75 mole (40 grams) of acrylonitrile, 0.19 mole (26 grams) of trichlorosilane, 0.75 mole (76 grams) of dichloro silane and 2 percent by weight of the reactants of triphenylphosphine. The vessel was sealed and heated, while being rocked, to a temperature of 100 C. for a period of two hours. The product obtained was placed in a flask connected to a distillation column and heated to its boiling temperature under a'jreduced pressure. There was obtained 14.4 grams of beta-cyanoethyldichlorosilane boiling at a temperatureof 50 to 52 C. under a reduced pressure of 2 mm. Hg. Beta-cyanoethyldichlorosilane was identified by infra-red analysis and by analysis for hydrolyzable chlorine (obtained 47.9 percent by weight, theory 46.0 percent by weight). The presence of a silicon to hydrogen bond. in beta-cyanoethyldichlorosilane was also proven by the evolution of hydrogen when the compound was added to an alcoholic caustic solution.

Example 13 1 To a 300 cc. steel pressure vessel were added 0.9 mole (102 grams) of methyldichlorosilane, 0.9 mole (48 grams) of acrylonitrile and 2 percent by weight of the reactants of triphenylphosphine. The vessel was sealed and heated,.while being rocked, to a temperature of 150 C. for a period of five hours. The product' obtained was placed in a'flask connected to a fractionating column and heated to its boiling temperature. Beta-.cyanoethylmethyldichlorosilane was obtained as a constant boiling product. There was also obtained a fraction identified as methyltrichlorosilane and a higher fraction (534 grams) boiling at 85 to 110..C. under a reduced pressure of 2mm. Hg. This high boiling product was identified as bis(cyanoethyl)methylchlorosilane by infra-red analysis and by analysis for hydrolyzable chlorine (obtained 18.3 percent-by weight, theory 18.9 percent by weight). Bis(cyanoethyl)methylchlorosilane is believed produced by the following reaction mechanism: Y

2MeSil-ICl -SMeSiI-I Cl+MeSiCl MeSiH- Cl+ 2CH :CH-CN 1 (CN---CH CH MeSiCl Example 14 Following the procedure disclosed in Example 1, 0.15

7 mole (20.3 grams) of trichlorosilane, 0.15 mole (8 grams) of acrylonitr'ile and 2 percent by weight of trin-butylphosphine were heated in a rocking pressure vessel to a temperature of 200 C. for a period of two hours. After heating, the vesselwas cooled to room temperature, the product removed therefrom and placed in a flask connected to a distillation column- The contents of the flask were heated to its. boiling temperature under reduced pressure and there was obtained 15,83 grams of beta=cyanoethyltrichlorosilane boiling at a temperature of 75 to 85 C. under a reduced pressure of to'7 mnLHg. .i 1 1 1'.

' Example -15 To a .300 cc. steel pressure vessel were added mole (47.8 grams) of acrylonitrile, 0.9 mole (121.9 grams) of trichlorosilane and 2.3 percent by weight of the reactants of triethylphosphine. The vessel was sealed and heated to a temperature of 150 C. for a period of two hours. After heating the vessel was cooled to room temperature, the product removed therefrom and placed in a flask connected to a distillation column. The contents of the flask were heated to its boiling temperature under a reduced pressure and there was distilled 93.2 grams of beta-cyanoethyltrichlorosilane. 7

Example 16 To a 300 cc. stainless steel pressure vessel was charged 0.9 mole (60.4 grams) of allyl cyanide, 0.9 mole (121.9 grams) of trichlorosilane and 2 percent by weight of the reactants of triphenylphosphine. The vessel was sealed and heated, while being rocked, to a temperature of 150 C. for a period of two hours. After heating the vessel was cooled to room temperature, the product removed therefrom and placed in a flask connected to a distillation column. The contents of the flask were heated to its boiling temperature under reduced pressure and there was obtained 56.89 grams of gamma-cyanopropyltrichlorosilane boiling at a temperature of 55 65" C. under a reduced pressure of .5 to .7 mm. Hg.

Example 17 To a one liter flask equipped with stirrer and reflux condenser were charged cc. of a 3 percent water solution of sodium hydroxide and 187 grams (1 mole) of beta-cyanoethylmethyldiethoxysilane dissolved in 400 cc. of diethyl ether. The mixture was stirred for a period of about 4 hours after which time it was heated under reduced pressure to distill the ether and the ethyl alcohol formed during the hydrolysis reaction. The product was washed with water until neutral and then dried over anhydrous sodium sulphate. The product was then added to a flask and heated under reduced pressureto distill any residual ether or alcohol content therein. There was obtained 68 grams of a colorless oil. The oil was then placed in' a flask connected to a Vigreaux column and heated to its boiling temperature. There was distilled 49 grams of the cyclic tetramer of beta-cyanoethylmethylsiloxane which was identified by elemental analysis as well as by infra-red analysis. Infra-red analysis of the product remaining in the flask resulted in the identification of the cyclic pentamer, hexamer and heptamer, of beta-cyanoethylmethylsiloxane. 1

The cyclictetramer of beta-cyanoethylmethylsiloxane has a boiling temperature of 277 to 280 C. under a reduced pessure of 0.2 mm. Hg and a refractive index 11 of 1.4580. The values appearing below were obtained from the elemental analysis of the compound and are compared with the corresponding calculated values.

To a beaker containing 400 cc. of cracked iceand 100 cc. of diethyl ether was added,,while stirring the mixture, 15.46 grams of beta-cyanoethyltrichlorosilane dissolved in 10 cc. of diethyl ether. During the addition of the solution of beta-cyanoethyltrichlorosilane hydrogen chloride was evolved. After the addition, the beaker was allowed to stand overnight" during which time the .diethyl ether evaporated and a thick syrup formed on 1the.bottom of thebe'aker. The syrup wasremoved from Y 13 the beaker, washed with distilled water until neutral and then de'solvate under reduced pressure at a-tempera ture of 25 C. for a period of 160 hours. There was obtained 8.08 grams of beta-cyanoethylpolysiloxane, lNcCH CHgSiOg l Beta 'cyanoethylpolysiloxane was identified by infra-red analysis and by elemental content. The table below contains the values obtained from our analysis as well as the corresponding'calculated values.

Example 19 A sample of the beta-cyanoethylpolysiloxane prepared in the previous example was placed in a Weighing bottle and the bottle placed in a forced draft air oven maintained at a temperature of 250 C. for a period of 96 hours. The weighin bottle was then removed from the oven and the polymer analyzed to determine the extent .of decomposition caused by the elevated temperature. A variation in the elemental content of the polymer before "and after heating is an indication of. the extent of decomposition In the sample tested, the beta-cyanoethylpolysil'oxane had a carbon content of 29.7 percentby weight before heating and a carbon content of 26.3 percent by weight after heating. Such values indicate that our beta-cyanoethylpolysiloxane retains 88.3 percent of its carbon content at elevated temperatures, which makes e polymers desirable as a protective coating. 1 What is claimed is:

1. A process for reacting a silane, represented by the formula:

where R represents a member of the group consisting of hydrogen and a hydrocarbylgroup, X represents a hydrolyzable group from the class consisting of halogen and hydrocarbyloxy groups and n represents a whole number having a value of from 0 to 2, with a monoolefinic aliphatic nitrile having from 3 to 10 carbon atoms and containing the unsaturated olefinic grouping (-C=C--) to produce a cyanoalkylsilane by the addition of a silyl group to the carbon atom of said unsaturated grouping further removed from the cyano group of said nitrile and by the addition of a hydrocarbon atom to the carbon atom of said unsaturated grouping closer to the cyano group of said nitrile which comprises forming a mixture of said silane, said nitrile and a trihydrocarbylphosphine, heating said mixture to a'temperature sutficiently elevated to cause said silane and nitrile to react to produce a cyanoalkylsilane by the addition of a s'ilyl group to the carbon atom of the unsaturated grouping further removed from the cyano group of the starting'nitrile and by the addition of a hydrogen atom to the carbon atom of the unsaturated grouping closer to the cyano group of the starting nitrile and recovering the cyanoalkylsilane.

2. A process for reacting a silane represented by the formula:

drolyzable group from the class consisting of a halogen atom and a hydrocarbyloxy group, and n represents a "14 whole number having a value offromO to with a nitrile having from 3 to 10 carbon atoms and the formula:

A R CH=( 3C N where R is a member of the group c-onsising of hy= drogen and an alkyl group and A is a member of the group consisting of a hydrogen atom and a methylgroup to produce a cyanoalkylsilane by the additionof a silyl group to the olefinic carbon atom of the nitrile further removed from the cyano group thereof and by the addition of a hydrogen atom to the olefinic carbon atom of jthe nitrile closer to the cyano group thereof which comprises forming a mixture of said silane, nitrile, and atrihydrocarbylphosphine, heating said mixture to a temperature sufficiently elevated to-cause said silane and nitrile to react to produce a cyanoalkylsilane by addition of a silyl group to the olefinic carbon atom, further removed from the cyano group of the startingnitrile and by the addition of a hydrogen atom to the olefinic carbon atom closer to the cyano group of the starting nitrile.

3. A process for producing a beta-eyanoethylsilane which comprises forming a mixture of a silane of the formula:

RIM) H-Si-Xat) where R represents a member of the group consisting of hydrogen and a hydrocarbyl group, X represents a hydrolyzable group from the class consisting of a halogen atom and a hydrocarbyloxy group and n represents a whole number having a value of from 0 to 2, aerylonipile and a trialkylphosphine catalyst, heating said mixture to a temperature suf'riciently.elevated to cause said silane and acryloni tn'le to react to produce a betacyano ethy lsilane.

4. A process for producing a beta-cyan'oethylsilane which comprises forming a mixture of a silane of the where R represents a member of the group consisting of hydrogen and a hydrocarby-l group, X re resent'sja hydrolyzable group taken from the class consisting of a halogen atom and a hydrocarbyloxy group and represents a whole number having a value of from Oft'o 2, acrylonitrile and a triarylphosphine catalyst, heating said mixture to a temperature sufliciently elevated to cause said silane and acrylonitrile to react to produce a beta cyanoethylsilane. r i

5. A process for producing gamma-cyanopropylsilane 'which comprises forming a mixture of a silane of the formula:

group consisting of which comprises forming a mixture of a silane of the formula:

\ H-SiX a-fl) where R represents a member of the group consisting of hydrogen and a hydrocarbyl group, X represents a hydrolyzable group taken from the class consisting of a halogen atom and a hydrocarbyloxy group and n represents a whole number having .a value of from 0 to 2, allyl cyanide and trialkylphosphine, heating said mixture to a temperature sufiiciently elevated to cause said silane and allyl cyanide to react to produce a gamma-cyanopropylsilane.

7. A process for producing beta-cyanoethyltrichlorosilane which comprises forming a mixture of acrylonitrile, trichlorosilane and triethylphosphine, heating said mixture to a temperature sufficiently elevated to cause said acrylonitrile and trichlorosilane to react to produce betacyanoethyltrichlorosilane.

8. A process for producing beta-cyanoethyltrichlorosilane which comprises forming a mixture of acrylonitrile, trichlorosilane and tri-n-butylphosphine, heating said mixture toa temperature sufficiently elevated to cause said.

acrylonitrile and trichlorosilane to react to produce a betacyanoethyltrichlorosilane. I

9. A process for producing gamma-cyanopropyltrichlorosilane which comprises forming a mixture of allyl cyanide, trichlorosilaneand triphenylphosphine, heating saidmixture to a temperature sufliciently elevated to cause said allyl cyanide and trichlorosilane to react to produce gamma-cyanopropyltrichlorosilane.

10. A process for producing a beta-cyanoethylalkyldichlorosilane which comprises forming a mixture of acrylonitrile, an alkyldichlorosilane and triphenylphosphine, heating said mixture to a temperature s'ufliciently elevated to cause said acyloni-trile and alkyldichlorosilane to react to produce a beta-cyanoethylalkyldichlorosilane.

11. A process for producing a beta-cyanoethylalkyldiethoxysilane which comprises forming a mixture of acrylo nitrile, an alkyldiethoxysilane and 'triphenylphosphine, heating said mixture to a temperature sufficiently ele- 'vated to cause said acrylonitrile and alkyldietho'xys'ilane toreact to produce. a beta-cyanoethylalkyldiethoxysilane.

12. A process for producing beta-cyanoethylmethyldichlorosilane which comprises forming a mixture comprising acrylonitrile, methyldichlorosilane and ftr'iphenylphosphine, heating said mixture to a temperature suffici'ently elevated to cause said acrylonitrile and methyldichlorosilane to react to produce beta-cyanoethylmethyldichlorosilane.

13. A process for producing beta-cyanoethylmethyldiethoxysilane which comprises forming a mixture compris mg acrylonitrile, methyldiethoxysilane and triphenylphosphine, heating said mixture to a temperature sufficiently elevated to cause said acrylonitrile and methyldiethoxysilane to react to produce beta-cyanoethylmethyldiethoxysilane. 1 i

14.,A' -pr0cess for producing beta cyanoethylethyldh chlorosilane whichcomprises forming a mixture compris-v ing acrylonitrile,,ethyldichlorosilane and. triphenylphosphine, heatingsaid mixture to a temperature sufficiently elevated to cause 'saidacrylo'nitrile" and ethyldi'chlo rosilane to react to produce 'beta-cyanoethylethyldichlorosilane. i 1

15. A process for producing beta-cyanoethyldichloroe silane which comprises forming a mixture comprising acrylonitrile, dichlorosilane and triphenylphosphine; heating said mixture to a temperature sufficiently elevated to cause said acrylonitrile and dichiorosilane to react to produce beta-cyanoethyldichlorosilane.

16. A process for producing beta-cyanoethyltrichlorosilane which comprises reacting acrylonitrile with'trichlorosilane in the presence of triphenylphosphine. 3 g

17. A process for producing beta-cyanopropyltrichlorm silane which comprises reacting methacrylonitrile with trichlorosilane in the presence of triphenylphosphine.

References Cited in the file of this patent 'UNITED STATES PATENTS I V 3 Oct. 3, 1950 2,524,529 Krieble 2,532,583 Tyran Dec. 5, 1950 2,557,802 Sorn-rner June 19, 1951 2,561,429 Sveda July 24, 1951 2,632,013 Wagner et a1. Mar. 17,1953 2,675,372 Coover et al. Apr. 13, 1954 2,701,803 Orkin Feb. 8; 1955 2,716,638 Cohen et a1 Aug. 30,- 1955 2,721,873 MacKenzie et -al.-' Oct. 25, 1955 2,776,306 Cole Jan. 1, 1957 2,823,218] Speier et a1. Feb. 1 1, 1958 I f FOREIGN PATENTS 1,116,725 --France; Feb. 6, 1956 1,116,726 France Feb. 6, 1956 786,020 Great Britain Nov, 6, 1957 OTHER REFERENCES Petrov et a1.: Doklady Akad. Nauk (U.S.S.R.), vol. (February 1955), pp. 711-14, Organosilicon Literature, vol. 8.

Prob er: Jr. Am; Chem. Soc, V0177 (June 1955), pp. 3224-8. 

1. A PROCESS FOR REACTING A SILANE, REPRESENTED BY THE FORMULA: 